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Kiontke K, Fernandez P, Woronik A, Fitch DHA. Morphologically defined substages of tail morphogenesis in C. elegans males. Dev Dyn 2024. [PMID: 38924277 DOI: 10.1002/dvdy.721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 05/01/2024] [Accepted: 05/31/2024] [Indexed: 06/28/2024] Open
Abstract
BACKGROUND Sex-specific morphogenesis occurs in Caenorhabditis elegans in the vulva of the hermaphrodite and in the male tail during the last larval stage. Temporal progression of vulva morphogenesis has been described in fine detail. However, a similar precise description of male tail morphogenesis was lacking. RESULTS We here describe morphogenesis of the male tail at time points matching vulva development with special focus on morphogenesis of the tail tip. Using fluorescent reporters, we follow changes in cell shapes, cell fusions, nuclear migration, modifications in the basement membrane, and formation of a new apical extracellular matrix at the end of the tail. CONCLUSION Our analysis answers two open questions about tail tip morphogenesis (TTM) by showing that one of the four tail tip cells, hyp11, remains largely separate, while the other cells fully fuse with each other and with two additional tail cells to form a ventral tail syncytium. This merger of cells begins at the apical surface early during TTM but is only completed toward the end of the process. This work provides a framework for future investigations of cell biological factors that drive male tail morphogenesis.
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Affiliation(s)
- Karin Kiontke
- Department of Biology, New York University, New York, New York, USA
| | | | | | - David H A Fitch
- Department of Biology, New York University, New York, New York, USA
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2
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Kiontke K, Fernandez P, Woronik A, Fitch DHA. Morphologically defined substages of tail morphogenesis in C. elegans males. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.11.575265. [PMID: 38293029 PMCID: PMC10827050 DOI: 10.1101/2024.01.11.575265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Background Sex-specific morphogenesis occurs in C. elegans in the vulva of the hermaphrodite and in the male tail during the last larval stage. Temporal progression of vulva morphogenesis has been described in fine detail. However, a similar precise description of male tail morphogenesis was lacking. Results We here describe morphogenesis of the male tail at time points matching vulva development with special focus on morphogenesis of the tail tip. Using fluorescent reporters, we follow changes in cell shapes, cell fusions, nuclear migration, modifications in the basement membrane and formation of a new apical extracellular matrix at the end of the tail. Conclusion Our analysis answers two open questions about tail tip morphogenesis (TTM) by showing that one of the four tail tip cells, hyp11, remains separate while the other cells fuse with each other and with two additional tail cells to form a ventral tail syncytium. This fusion begins early during TTM but is only completed towards the end of the process. This work provides a framework for future investigations of cell-biological factors that drive male tail morphogenesis.
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Affiliation(s)
- Karin Kiontke
- Department of Biology, New York University, 100 Washington Square E., New York, NY 10003
| | - Porfirio Fernandez
- Department of Biology, New York University, 100 Washington Square E., New York, NY 10003
| | - Alyssa Woronik
- Sacred Heart University, 5151 Park Avenue, Fairfield, CT 06825
| | - David H A Fitch
- Department of Biology, New York University, 100 Washington Square E., New York, NY 10003
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3
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Fung W, Tan TM, Kolotuev I, Heiman MG. A sex-specific switch in a single glial cell patterns the apical extracellular matrix. Curr Biol 2023; 33:4174-4186.e7. [PMID: 37708887 PMCID: PMC10578079 DOI: 10.1016/j.cub.2023.08.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 07/17/2023] [Accepted: 08/16/2023] [Indexed: 09/16/2023]
Abstract
Apical extracellular matrix (aECM) constitutes the interface between every tissue and the outside world. It is patterned into diverse tissue-specific structures through unknown mechanisms. Here, we show that a male-specific genetic switch in a single C. elegans glial cell patterns the overlying aECM from a solid sheet to an ∼200 nm pore, thus allowing a male sensory neuron to access the environment. Using cell-specific genetic sex reversal, we find that this switch reflects an inherent sex difference in the glial cell that is independent of the sex identity of the surrounding neurons. Through candidate and unbiased genetic screens, we find that this glial sex difference is controlled by factors shared with neurons (mab-3, lep-2, and lep-5) as well as previously unidentified regulators whose effects may be glia specific (nfya-1, bed-3, and jmjd-3.1). The switch results in male-specific glial expression of a secreted Hedgehog-related protein, GRL-18, that we discover localizes to transient nanoscale rings at sites where aECM pores will form. Using electron microscopy, we find that blocking male-specific gene expression in glia prevents pore formation, whereas forcing male-specific glial gene expression induces an ectopic pore. Thus, a switch in gene expression in a single cell is necessary and sufficient to pattern aECM into a specific structure. Our results highlight that aECM is not a simple homogeneous meshwork, but instead is composed of discrete local features that reflect the identity of the underlying cells.
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Affiliation(s)
- Wendy Fung
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA
| | - Taralyn M Tan
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA
| | - Irina Kolotuev
- Electron Microscopy Facility, University of Lausanne, 1015 Lausanne, Switzerland
| | - Maxwell G Heiman
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA.
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Fung W, Tan TM, Kolotuev I, Heiman MG. A sex-specific switch in a single glial cell patterns the apical extracellular matrix. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.17.533199. [PMID: 36993293 PMCID: PMC10055199 DOI: 10.1101/2023.03.17.533199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Apical extracellular matrix (aECM) constitutes the interface between every tissue and the outside world. It is patterned into diverse tissue-specific structures through unknown mechanisms. Here, we show that a male-specific genetic switch in a single C. elegans glial cell patterns the aECM into a ∼200 nm pore, allowing a male sensory neuron to access the environment. We find that this glial sex difference is controlled by factors shared with neurons ( mab-3, lep-2, lep-5 ) as well as previously unidentified regulators whose effects may be glia-specific ( nfya-1, bed-3, jmjd-3.1 ). The switch results in male-specific expression of a Hedgehog-related protein, GRL-18, that we discover localizes to transient nanoscale rings at sites of aECM pore formation. Blocking male-specific gene expression in glia prevents pore formation, whereas forcing male-specific expression induces an ectopic pore. Thus, a switch in gene expression in a single cell is necessary and sufficient to pattern aECM into a specific structure.
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Affiliation(s)
- Wendy Fung
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children’s Hospital, Boston, MA 02115, USA
| | - Taralyn M. Tan
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children’s Hospital, Boston, MA 02115, USA
| | - Irina Kolotuev
- Electron Microscopy Facility, University of Lausanne, 1015 Lausanne, Switzerland
| | - Maxwell G. Heiman
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children’s Hospital, Boston, MA 02115, USA
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Suzuki N, Zou Y, Sun H, Eichel K, Shao M, Shih M, Shen K, Chang C. Two intrinsic timing mechanisms set start and end times for dendritic arborization of a nociceptive neuron. Proc Natl Acad Sci U S A 2022; 119:e2210053119. [PMID: 36322763 PMCID: PMC9659368 DOI: 10.1073/pnas.2210053119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 10/04/2022] [Indexed: 11/05/2022] Open
Abstract
Choreographic dendritic arborization takes place within a defined time frame, but the timing mechanism is currently not known. Here, we report that the precisely timed lin-4-lin-14 regulatory circuit triggers an initial dendritic growth activity, whereas the precisely timed lin-28-let-7-lin-41 regulatory circuit signals a subsequent developmental decline in dendritic growth ability, hence restricting dendritic arborization within a set time frame. Loss-of-function mutations in the lin-4 microRNA gene cause limited dendritic outgrowth, whereas loss-of-function mutations in its direct target, the lin-14 transcription factor gene, cause precocious and excessive outgrowth. In contrast, loss-of-function mutations in the let-7 microRNA gene prevent a developmental decline in dendritic growth ability, whereas loss-of-function mutations in its direct target, the lin-41 tripartite motif protein gene, cause further decline. lin-4 and let-7 regulatory circuits are expressed in the right place at the right time to set start and end times for dendritic arborization. Replacing the lin-4 upstream cis-regulatory sequence at the lin-4 locus with a late-onset let-7 upstream cis-regulatory sequence delays dendrite arborization, whereas replacing the let-7 upstream cis-regulatory sequence at the let-7 locus with an early-onset lin-4 upstream cis-regulatory sequence causes a precocious decline in dendritic growth ability. Our results indicate that the lin-4-lin-14 and the lin-28-let-7-lin-41 regulatory circuits control the timing of dendrite arborization through antagonistic regulation of the DMA-1 receptor level on dendrites. The LIN-14 transcription factor likely directly represses dma-1 gene expression through a transcriptional means, whereas the LIN-41 tripartite motif protein likely indirectly promotes dma-1 gene expression through a posttranscriptional means.
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Affiliation(s)
- Nobuko Suzuki
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607
| | - Yan Zou
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - HaoSheng Sun
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35233
| | - Kelsie Eichel
- HHMI, Stanford University, Stanford, CA 94305
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Meiyu Shao
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Mushaine Shih
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607
| | - Kang Shen
- HHMI, Stanford University, Stanford, CA 94305
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Chieh Chang
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607
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Wang D, Tanaka-Yano M, Meader E, Kinney MA, Morris V, Lummertz da Rocha E, Liu N, Liu T, Zhu Q, Orkin SH, North TE, Daley GQ, Rowe RG. Developmental maturation of the hematopoietic system controlled by a Lin28b-let-7-Cbx2 axis. Cell Rep 2022; 39:110587. [PMID: 35385744 PMCID: PMC9029260 DOI: 10.1016/j.celrep.2022.110587] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 12/13/2021] [Accepted: 03/08/2022] [Indexed: 01/06/2023] Open
Abstract
Hematopoiesis changes over life to meet the demands of maturation and aging. Here, we find that the definitive hematopoietic stem and progenitor cell (HSPC) compartment is remodeled from gestation into adulthood, a process regulated by the heterochronic Lin28b/let-7 axis. Native fetal and neonatal HSPCs distribute with a pro-lymphoid/erythroid bias with a shift toward myeloid output in adulthood. By mining transcriptomic data comparing juvenile and adult HSPCs and reconstructing coordinately activated gene regulatory networks, we uncover the Polycomb repressor complex 1 (PRC1) component Cbx2 as an effector of Lin28b/let-7's control of hematopoietic maturation. We find that juvenile Cbx2-/- hematopoietic tissues show impairment of B-lymphopoiesis, a precocious adult-like myeloid bias, and that Cbx2/PRC1 regulates developmental timing of expression of key hematopoietic transcription factors. These findings define a mechanism of regulation of HSPC output via chromatin modification as a function of age with potential impact on age-biased pediatric and adult blood disorders.
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Affiliation(s)
- Dahai Wang
- Department of Hematology/Oncology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Mayuri Tanaka-Yano
- Department of Hematology/Oncology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Eleanor Meader
- Stem Cell Program, Boston Children's Hospital, Boston, MA 02115, USA
| | - Melissa A Kinney
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Vivian Morris
- Stem Cell Program, Boston Children's Hospital, Boston, MA 02115, USA
| | - Edroaldo Lummertz da Rocha
- Department of Microbiology, Immunology, and Parasitology, Federal University of Santa Catarina, Florianopolis 88040-900, Brazil
| | - Nan Liu
- Department of Hematology/Oncology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Tianxin Liu
- Department of Hematology/Oncology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Qian Zhu
- Department of Hematology/Oncology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Stuart H Orkin
- Department of Hematology/Oncology, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA; Dana-Farber Boston Children's Cancer and Blood Disorders Center, Boston, MA 02115, USA
| | - Trista E North
- Stem Cell Program, Boston Children's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA
| | - George Q Daley
- Department of Hematology/Oncology, Boston Children's Hospital, Boston, MA 02115, USA; Stem Cell Program, Boston Children's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA
| | - R Grant Rowe
- Department of Hematology/Oncology, Boston Children's Hospital, Boston, MA 02115, USA; Stem Cell Program, Boston Children's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA; Dana-Farber Boston Children's Cancer and Blood Disorders Center, Boston, MA 02115, USA; Stem Cell Transplantation Program, Boston Children's Hospital, Boston, MA 02115, USA.
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Du X, Li Q, Yang L, Zeng Q, Wang S, Li Q. Transcriptomic Data Analyses Reveal That Sow Fertility-Related lincRNA NORFA Is Essential for the Normal States and Functions of Granulosa Cells. Front Cell Dev Biol 2021; 9:610553. [PMID: 33708768 PMCID: PMC7940361 DOI: 10.3389/fcell.2021.610553] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 01/25/2021] [Indexed: 12/13/2022] Open
Abstract
NORFA, the first lincRNA associated with sow fertility, has been shown to control granulosa cell (GC) functions and follicular atresia. However, the underlying mechanism is not fully understood. In this study, RNA-seq was performed and we noticed that inhibition of NORFA led to dramatic transcriptomic alterations in porcine GCs. A total of 1,272 differentially expressed transcripts were identified, including 1167 DEmRNAs and 105 DEmiRNAs. Furthermore, protein–protein interaction, gene-pathway function, and TF–miRNA–mRNA regulatory networks were established and yielded four regulatory modules with multiple hub genes, such as AR, ATG5, BAK1, CENPE, NR5A1, NFIX, WNT5B, ssc-miR-27b, and ssc-miR-126. Functional assessment showed that these hub DEGs were mainly enriched in TGF-β, PI3K-Akt, FoxO, Wnt, MAPK, and ubiquitin pathways that are essential for GC states (apoptosis and proliferation) and functions (hormone secretion). In vitro, we also found that knockdown of NORFA in porcine GCs significantly induced cell apoptosis, impaired cell viability, and suppressed 17β-estradiol (E2) synthesis. Notably, four candidate genes for sow reproductive traits (INHBA, NCOA1, TGFβ-1, and TGFBR2) were also identified as potential targets of NORFA. These findings present a panoramic view of the transcriptome in NORFA-reduced GCs, highlighting that NORFA, a candidate lincRNA for sow fertility, is crucial for the normal states and functions of GCs.
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Affiliation(s)
- Xing Du
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Qiqi Li
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Liu Yang
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Qiang Zeng
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Siqi Wang
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Qifa Li
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
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8
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Chen H, Shan G. The physiological function of long-noncoding RNAs. Noncoding RNA Res 2020; 5:178-184. [PMID: 32959025 PMCID: PMC7494506 DOI: 10.1016/j.ncrna.2020.09.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 09/15/2020] [Indexed: 12/11/2022] Open
Abstract
The physiological processes of cells and organisms are regulated by various biological macromolecules, including long-noncoding RNAs (lncRNAs), which cannot be translated into protein and are different from small-noncoding RNAs on their length. In animals, lncRNAs are involved in development, metabolism, reproduction, aging and other life events by cis or trans effects. For many functional lncRNAs, there is growing evidence that they play different roles on cellular level and organismal level. On the other hand, many annotated lncRNAs are not essential and could be transcription noises. In this minireview, we investigate the physiological function of lncRNAs in cells and focus on their functions and functional mechanisms on the organismal level. The studies on lncRNAs using different classic animal models such as worms and flies are summarized and discussed in this article.
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Affiliation(s)
- He Chen
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province, 230027, China
| | - Ge Shan
- CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS Center for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province, 230027, China
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Lawson HN, Wexler LR, Wnuk HK, Portman DS. Dynamic, Non-binary Specification of Sexual State in the C. elegans Nervous System. Curr Biol 2020; 30:3617-3623.e3. [PMID: 32707065 DOI: 10.1016/j.cub.2020.07.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 06/29/2020] [Accepted: 07/01/2020] [Indexed: 12/21/2022]
Abstract
Biological sex in animals is often considered a fixed, individual-level characteristic. However, not all sex-specific features are static: for example, C. elegans males (XO) can sometimes exhibit hermaphrodite (XX)-like feeding behavior [1, 2]. (C. elegans hermaphrodites are somatic females that transiently produce self-sperm.) Essentially all somatic sex differences in C. elegans are governed by the master regulator tra-1, whose activity is controlled by chromosomal sex and is necessary and sufficient to specify the hermaphrodite state [3]. One aspect of this state is high expression of the chemoreceptor odr-10. In hermaphrodites, high odr-10 expression promotes feeding, but in males, low odr-10 expression facilitates exploration [4]. However, males suppress this sex difference in two contexts: juvenile males exhibit high odr-10 expression and food deprivation activates odr-10 in adult males [4-6]. Remarkably, we find that both of these phenomena require tra-1. In juvenile (L3) males, tra-1 is expressed in numerous neurons; this expression diminishes as individuals mature into adulthood, a process that requires conserved regulators of sexual maturation. tra-1 remains expressed in a small number of neurons in adult males, where it likely has a permissive role in odr-10 activation. Thus, the neuronal functions of tra-1 are not limited to hermaphrodites; rather, tra-1 also acts in the male nervous system to transiently suppress a sexual dimorphism, developmentally and in response to nutritional stress. Our results show that the molecular and functional representation of sexual state in C. elegans is neither static nor homogeneous, challenging traditional notions about the nature of biological sex.
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Affiliation(s)
- Hannah N Lawson
- Department of Biology, University of Rochester, Rochester, NY, USA
| | - Leigh R Wexler
- Department of Biomedical Genetics, University of Rochester, Rochester, NY, USA
| | - Hayley K Wnuk
- Department of Biology, University of Rochester, Rochester, NY, USA
| | - Douglas S Portman
- Department of Biology, University of Rochester, Rochester, NY, USA; Department of Biomedical Genetics, University of Rochester, Rochester, NY, USA; Ernest J. Del Monte Institute for Neuroscience, University of Rochester, Rochester, NY, USA.
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Lawson H, Vuong E, Miller RM, Kiontke K, Fitch DH, Portman DS. The Makorin lep-2 and the lncRNA lep-5 regulate lin-28 to schedule sexual maturation of the C. elegans nervous system. eLife 2019; 8:43660. [PMID: 31264582 PMCID: PMC6606027 DOI: 10.7554/elife.43660] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 05/10/2019] [Indexed: 12/30/2022] Open
Abstract
Sexual maturation must occur on a controlled developmental schedule. In mammals, Makorin3 (MKRN3) and the miRNA regulators LIN28A/B are key regulators of this process, but how they act is unclear. In C. elegans, sexual maturation of the nervous system includes the functional remodeling of postmitotic neurons and the onset of adult-specific behaviors. Here, we find that the lin-28–let-7 axis (the ‘heterochronic pathway’) determines the timing of these events. Upstream of lin-28, the Makorin lep-2 and the lncRNA lep-5 regulate maturation cell-autonomously, indicating that distributed clocks, not a central timer, coordinate sexual differentiation of the C. elegans nervous system. Overexpression of human MKRN3 delays aspects of C. elegans sexual maturation, suggesting the conservation of Makorin function. These studies reveal roles for a Makorin and a lncRNA in timing of sexual differentiation; moreover, they demonstrate deep conservation of the lin-28–let-7 system in controlling the functional maturation of the nervous system. Most animals develop from juveniles, which cannot reproduce, to sexually mature adults. The most obvious signs of this transition are changes in body shape and size. However, changes also take place in the brain that enable the animals to adapt their behavior to the demands of adulthood. For example, fully fed adult male roundworms will leave a food source to search for mates, whereas juvenile males will continue feeding. The transition to sexual maturity needs to be carefully timed. Too early, and the animal risks compromising key stages of development. Too late, and the animal may be less competitive in the quest for reproductive success. Cues in the environment, such as the presence of food and mates, interact with timing mechanisms in the brain to trigger sexual maturity. But how these mechanisms work – in particular where and how an animal keeps track of its developmental stage – is not well understood. In the roundworm species Caenorhabditis elegans, waves of gene activity, known collectively as the heterochronic pathway, determine patterns of cell growth as animals mature. Through further studies of these worms, Lawson et al. now show that these waves also control the time at which neural circuits mature. In addition, the waves of activity occur inside the nervous system itself, rather than in a tissue that sends signals to the nervous system. Moreover, they occur independently inside many different neurons. Each neuron thus has its own molecular clock for keeping track of development. Several of the genes critical for developmental timekeeping in worms are also found in mammals, including two genes that help to control when puberty starts in humans. If one of these genes – called MKRN3 – does not work correctly, it can lead to a condition that causes individuals to go through puberty several years earlier than normal. Studying the mechanisms identified in roundworms may help us to better understand this disorder. More generally, future work that builds on the results presented by Lawson et al. will help to reveal how environmental cues and gene activity interact to control when we become adults.
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Affiliation(s)
- Hannah Lawson
- Department of Biology, University of Rochester, Rochester, United States
| | - Edward Vuong
- Department of Biomedical Genetics, University of Rochester, Rochester, United States
| | - Renee M Miller
- Department of Brain and Cognitive Sciences, University of Rochester, Rochester, United States
| | - Karin Kiontke
- Center for Developmental Genetics, Department of Biology, New York University, New York, United States
| | - David Ha Fitch
- Center for Developmental Genetics, Department of Biology, New York University, New York, United States
| | - Douglas S Portman
- Department of Biology, University of Rochester, Rochester, United States.,Department of Biomedical Genetics, University of Rochester, Rochester, United States.,Department of Neuroscience, University of Rochester, Rochester, United States.,DelMonte Institute for Neuroscience, University of Rochester, Rochester, United States
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